<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let sun = prompt('请输入星期数');

        switch (sun) {
            case '星期一':
                alert('monday');
                break;
            case '星期二':
                alert('tuesday');
                break;
            case '星期三':
                alert('Wednesday');
                break;
            case '星期四':
                alert('Thursday');
                break;
            case '星期五':
                alert('Friday');
                break;
            case '星期六':
                alert('Saturday');
                break;
            case '星期日':
                alert('Sunday');
                break;
        };
    </script>
</body>

</html>